Hydrothermal co-production and co-transport system combined with waste heat recovery of power plant and operation method thereof

Abstract

This invention relates to the field of heating technology, and more particularly to a water and heat co-generation and transmission system and its operation method that combines power plant waste heat recovery. In this system, high-grade exhaust steam generated by the main turbine is fed into a small turbine for power generation, while low-grade exhaust steam generated by the main turbine is fed into a seawater desalination unit. The seawater desalination unit separates seawater into fresh water and saline, with the fresh water flowing into a waste heat recovery unit and / or a water consumption unit. The power generation unit provides electricity to an electric heat pump and a thermal storage boiler. The low-grade exhaust steam generated by the main turbine heats the fresh water flowing in the electric heat pump and absorption heat pump, respectively. The high-grade exhaust steam generated by the small turbine and / or the thermal storage boiler heats the fresh water flowing in the absorption heat pump and the peak heat exchanger, respectively. After being heated by the electric heat pump and / or the absorption heat pump and peak heat exchanger connected in series, the fresh water flows to a water-heat separation unit, which reduces the temperature of the fresh water. The cooled fresh water then flows into the water consumption unit.

Description

Technical Field

[0001] This invention relates to the field of heating technology, and in particular to a water and heat co-generation and co-transmission system that combines power plant waste heat recovery with its operation method. Background Technology

[0002] my country's spatial distribution pattern of abundant water resources in the south and scarce water resources in the north determines that the northern region has a relatively poor water endowment. Under current technology, water and heat transmission are often achieved through independent pipelines, resulting in high investment costs, significant operational losses, and low efficiency. Furthermore, traditional thermal power plants mainly operate on a "heat-driven power generation" model, meaning that power generation is determined by heating demand. This significantly reduces the power generation regulation capacity of the heating units. At the same time, the gradual increase in installed capacity of renewable energy in recent years, along with the intermittent, fluctuating, and random characteristics of renewable energy sources such as wind and solar power, has further increased the regulation pressure on generator units and led to severe wind and solar curtailment.

[0003] Therefore, there is an urgent need to design a water and heat co-generation and co-transmission system and operation method that combines power plant waste heat recovery to solve the above technical problems. Summary of the Invention

[0004] One objective of this invention is to propose a water-heat co-generation and co-transmission system that combines power plant waste heat recovery, so as to reduce energy loss in the transmission and distribution process, improve the system's heating economy, enhance the unit's power generation regulation capability, realize peak shaving and valley filling of power load, and ensure the power plant operates under stable conditions.

[0005] To achieve this objective, the present invention adopts the following technical solution: A water and heat co-generation and co-transmission system combining power plant waste heat recovery is provided, including a power generation unit, a seawater desalination unit, a waste heat recovery unit, a water and heat separation unit, and a water use unit; The power generation unit includes a main steam turbine and a small steam turbine. Main steam is fed into the main steam turbine to generate electricity. High-grade exhaust steam generated by the main steam turbine is fed into the small steam turbine to generate electricity. Low-grade exhaust steam generated by the main steam turbine is fed into the seawater desalination unit. The seawater desalination unit is used to separate seawater into fresh water and saline. The fresh water is fed into the waste heat recovery unit and / or the water use unit. The waste heat recovery unit includes an electric heat pump, an absorption heat pump, a peak heat exchanger, and a thermal storage electric boiler. The power generation unit is used to provide electricity to the electric heat pump and the thermal storage electric boiler. The low-grade exhaust steam generated by the main steam turbine heats the fresh water flowing in the electric heat pump and the absorption heat pump, respectively. The high-grade exhaust steam generated by the small steam turbine and / or the thermal storage electric boiler heat the fresh water flowing in the absorption heat pump and the peak heat exchanger, respectively. The waste heat recovery unit has a first water path including the cold side of the electric heat pump and a second water path including the cold side of the absorption heat pump connected in series and the cold side of the peak heat exchanger. Fresh water is connected to the water-heat separation unit through the first water path and / or the second water path. The water-heat separation unit is used to reduce the temperature of the fresh water, and the cooled fresh water is directed to the water use unit.

[0006] Optionally, the combined water and heat production and transmission system integrating power plant waste heat recovery further includes a combined supply and transmission pipeline, through which the first water path and the second water path are connected to the water and heat separation unit, and through which the freshwater outlet of the seawater desalination unit is connected to the water-using unit.

[0007] Optionally, the waste heat recovery unit further includes a first valve and a first pipeline, the first water path being connected to the combined power supply pipeline through the first pipeline, and the first valve being disposed on the first pipeline; The waste heat recovery unit also includes a second valve and a second pipeline. The second water path is connected to the combined power supply pipeline through the second pipeline, and the second valve is installed in the second pipeline. The seawater desalination unit also includes a third valve and a third pipeline. The freshwater outlet of the seawater desalination unit is connected to the combined supply and delivery pipeline through the third pipeline, and the third valve is located on the third pipeline.

[0008] Optionally, the water-heat separation unit further includes a fourth valve and a fourth pipeline, the water-heat separation unit being connected to the combined power supply pipeline via the fourth pipeline, and the fourth valve being disposed on the fourth pipeline; The water-using unit also includes a fifth valve and a fifth pipeline. The water-using unit is connected to the combined power supply pipeline through the fifth pipeline, and the fifth valve is located on the fifth pipeline.

[0009] Optionally, the water-heat separation unit includes multiple user-end heating devices arranged in parallel, the fourth pipeline includes a fourth main pipe and multiple fourth branch pipes, one of the fourth branch pipes is connected to one user-end heating device, the fourth main pipe is connected to the combined supply and delivery pipeline, and the fourth valve is provided on the fourth main pipe.

[0010] Optionally, the waste heat recovery unit further includes a sixth valve and a sixth pipeline. The sixth valve is located on the sixth pipeline. The thermal storage electric boiler is connected to the hot side of the peak heat exchanger and the hot side of the absorption heat pump through the sixth pipeline. The hot side of the peak heat exchanger and the hot side of the absorption heat pump are connected to the exhaust port of the small steam turbine.

[0011] Optionally, the sixth valve includes a sixth outlet valve and a sixth inlet valve, the sixth pipeline includes a sixth outlet pipeline and a sixth inlet pipeline, the sixth outlet valve is disposed in the sixth outlet pipeline, and the sixth inlet valve is disposed in the sixth inlet pipeline; The outlet of the thermal storage electric boiler is connected to the hot-side inlet of the peak heat exchanger and the hot-side inlet of the absorption heat pump via the sixth outlet pipe, and the inlet of the thermal storage electric boiler is connected to the hot-side outlet of the peak heat exchanger and the hot-side outlet of the absorption heat pump via the sixth inlet pipe.

[0012] Optionally, the power generation unit further includes a cooling unit, which is connected to the exhaust steam port of the main steam turbine and the exhaust steam port of the small steam turbine; The cooling unit is also connected to the hot-side outlet of the seawater desalination unit, the hot-side outlet of the electric heat pump, the hot-side outlet of the absorption heat pump, and the hot-side outlet of the peak heat exchanger.

[0013] Another objective of this invention is to propose an operating method to reduce energy loss during transmission and distribution, improve the economic efficiency of system heating, enhance the power generation regulation capability of the unit, achieve peak shaving and valley filling of power load, and ensure that the power plant operates under stable conditions.

[0014] To achieve this objective, the present invention adopts the following technical solution: An operating method is provided for the above-mentioned combined hydro-heat generation and transmission system integrating power plant waste heat recovery, the operating method comprising the following steps: The combined water and heat production and transmission system that integrates power plant waste heat recovery is in non-heating mode. The main steam turbine and the seawater desalination unit are in operation. The low-grade exhaust steam generated by the main steam turbine preheats the seawater desalination unit, and the fresh water from the seawater desalination unit is supplied to the water-using unit. The combined water and heat production and transmission system integrating power plant waste heat recovery is in heating mode. The seawater desalination unit, the main steam turbine, the small steam turbine, the electric heat pump, the absorption heat pump, and the peak heat exchanger are all in operation. The high-grade exhaust steam generated by the main steam turbine is fed into the small steam turbine for power generation. The low-grade exhaust steam generated by the main steam turbine preheats the seawater desalination unit. The freshwater from the seawater desalination unit is heated through the first water path and the second water path and then flows into the water-heat separation unit. The water-heat separation unit is used to reduce the temperature of the freshwater. The cooled freshwater is then fed into the water-using unit. The combined hydro-thermal system, which integrates power plant waste heat recovery, operates under a high electricity price mode. The seawater desalination unit, the main steam turbine, the absorption heat pump, and the peak heat exchanger are all in operation. The thermal storage electric boiler operates in a heat release mode. The low-grade exhaust steam generated by the main steam turbine preheats the seawater desalination unit. The freshwater from the seawater desalination unit is heated through the second water path and then flows into the hydro-thermal separation unit. The hydro-thermal separation unit is used to reduce the temperature of the freshwater. The cooled freshwater then flows to the water-using unit. The combined hydro-thermal system, which integrates power plant waste heat recovery, operates in a low-electricity-price mode. The seawater desalination unit, the main steam turbine, the small steam turbine, the absorption heat pump, and the peak heat exchanger are all operational. The thermal storage electric boiler operates in thermal storage mode. High-grade exhaust steam generated by the main steam turbine is fed into the small steam turbine for power generation. Low-grade exhaust steam generated by the main steam turbine preheats the seawater desalination unit. The freshwater from the seawater desalination unit is heated through the first and second water paths before flowing into the hydro-thermal separation unit. The hydro-thermal separation unit is used to reduce the temperature of the freshwater, which is then fed into the water-using unit.

[0015] Optionally, the operating method includes the following steps: The combined water and heat production and transmission system integrating power plant waste heat recovery is in non-heating mode. The first, second, and sixth valves of the waste heat recovery unit are closed, the fourth valve of the water and heat separation unit is closed, the third valve of the seawater desalination unit is open, and the fifth valve of the water use unit is open. The combined water and heat production and transmission system integrating power plant waste heat recovery is in heating mode. The first, second, and sixth valves of the waste heat recovery unit are open, the fourth valve of the water and heat separation unit is open, the third valve of the seawater desalination unit is closed, and the fifth valve of the water use unit is closed. The combined water and heat production and transmission system integrating power plant waste heat recovery is in a high electricity price mode. The second and sixth valves of the waste heat recovery unit are open, the fourth valve of the water and heat separation unit is open, the first valve of the waste heat recovery unit is closed, the third valve of the seawater desalination unit is closed, and the fifth valve of the water use unit is closed. The combined water and heat production and transmission system integrating power plant waste heat recovery is in a low electricity price mode. The first and second valves of the waste heat recovery unit are open, the fourth valve of the water and heat separation unit is open, the sixth valve of the waste heat recovery unit is closed, the third valve of the seawater desalination unit is closed, and the fifth valve of the water use unit is closed.

[0016] The beneficial effects of the present invention include at least the following: This invention provides a hydrothermal co-generation and co-transmission system integrating power plant waste heat recovery, comprising a power generation unit, a seawater desalination unit, a waste heat recovery unit, a hydrothermal separation unit, and a water consumption unit. The power generation unit includes a main steam turbine and a small steam turbine. Main steam is fed into the main steam turbine to generate electricity. High-grade exhaust steam generated by the main steam turbine is fed into the small steam turbine to generate electricity. Low-grade exhaust steam generated by the main steam turbine is fed into the seawater desalination unit, which separates seawater into fresh water and saline. The fresh water is then fed into the waste heat recovery unit and / or the water consumption unit. The waste heat recovery unit includes an electric heat pump, an absorption heat pump, a peak heat exchanger, and a thermal storage electric boiler. The power generation unit provides electricity to the electric heat pump and the thermal storage electric boiler. The low-grade exhaust steam generated by the main steam turbine heats the fresh water flowing within the electric heat pump and the absorption heat pump, respectively. The high-grade exhaust steam generated by the small steam turbine and / or the thermal storage electric boiler heat the fresh water flowing within the absorption heat pump and the peak heat exchanger, respectively. The waste heat recovery unit has a first water path on the cold side, including an electric heat pump, and a second water path on the cold side, including a series-connected absorption heat pump and a peak heat exchanger. The electric heat pump, absorption heat pump, and peak heat exchanger all have cold and hot sides. The hot side flows from the heat source of the power generation unit (low-grade exhaust steam from the main turbine and high-grade exhaust steam from the small turbine), while the cold side flows from fresh water from the seawater desalination unit. A water-heat separation unit is connected to the first and / or second water paths. The water-heat separation unit is used to reduce the temperature of the fresh water, which is then supplied to the water-using unit. That is, the fresh water separated by the seawater desalination unit can be heated by the electric heat pump and / or sequentially by the absorption heat pump and peak heat exchanger to become hot water. The hot water is then transported to the water-heat separation unit where it is cooled by consuming heat. The cooled fresh water is then supplied to the water-using unit, thus achieving simultaneous production and transportation of water and heat during long-distance transport. Secondly, in environments where heat is not required, the water-using unit can be directly connected to the seawater desalination unit, meaning that the fresh water separated by the seawater desalination unit can be directly supplied to the water-using unit without heating.

[0017] This integrated water and heat production and transmission system, combining waste heat recovery from power plants, merges the water and heat transmission paths into one. It also incorporates a small steam turbine and a waste heat recovery unit to further utilize the waste heat from the main steam turbine. This system can transport water and heat from southern regions to northern regions, addressing the widespread water and heat shortages in the north. Simultaneously, it reduces operating costs, improves system efficiency, and achieves clean and low-carbon development. Secondly, by setting up two modes—direct freshwater transmission and freshwater heated by the waste heat recovery unit before transmission—the system can operate in both heating and non-heating modes, enabling year-round operation and expanding its application scenarios. Furthermore, the waste heat recovery unit includes various heat exchange and storage devices such as electric heat pumps, absorption heat pumps, peak heat exchangers, and thermal storage boilers. This ensures the power generation unit can maintain grid connection during periods of high electricity prices, while absorbing excess electricity during periods of low electricity prices. This further reduces costs and also plays a role in peak shaving and valley filling, assisting in power system regulation.

[0018] This invention provides an operating method for the aforementioned integrated water and heat production and transmission system combining power plant waste heat recovery, comprising the following steps: In a non-heating mode, the integrated water and heat production and transmission system combining power plant waste heat recovery operates with the main steam turbine and seawater desalination unit. The low-grade exhaust steam generated by the main steam turbine preheats the seawater desalination unit, and the freshwater from the seawater desalination unit flows to the water-using unit. In a heating mode, the integrated water and heat production and transmission system combining power plant waste heat recovery operates with the seawater desalination unit, main steam turbine, small steam turbine, electric heat pump, absorption heat pump, and peak heat exchanger all operating. The high-grade exhaust steam generated by the main steam turbine is fed into the small steam turbine for power generation. The low-grade exhaust steam generated by the main steam turbine preheats the seawater desalination unit. The freshwater from the seawater desalination unit, after being heated through a first water path and a second water path, flows into a water-heat separation unit. The water-heat separation unit is used to reduce the temperature of the freshwater, and the cooled freshwater flows to the water-using unit. In the high-electricity-price mode, the seawater desalination unit, main steam turbine, absorption heat pump, and peak heat exchanger are all operating. The thermal storage boiler operates in heat release mode. The low-grade exhaust steam generated by the main steam turbine preheats the seawater desalination unit. The freshwater from the seawater desalination unit is heated through the second water path and then flows into the water-heat separation unit. The water-heat separation unit is used to reduce the temperature of the freshwater, and the cooled freshwater is then sent to the water-using unit. In the low-electricity-price mode, the water-heat co-production and co-transmission system combined with waste heat recovery of the power plant operates. The seawater desalination unit, main steam turbine, small steam turbine, absorption heat pump, and peak heat exchanger are all operating. The thermal storage boiler operates in heat storage mode. The high-grade exhaust steam generated by the main steam turbine is fed into the small steam turbine for power generation. The low-grade exhaust steam generated by the main steam turbine preheats the seawater desalination unit. The freshwater from the seawater desalination unit is heated through the first and second water paths and then flows into the water-heat separation unit. The water-heat separation unit is used to reduce the temperature of the freshwater, and the cooled freshwater is then sent to the water-using unit. Attached Figure Description

[0019] Figure 1 This is a partial structural schematic diagram of the hydro-heat co-generation and co-transmission system combining power plant waste heat recovery provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the hydro-heat co-generation and co-transmission system combining power plant waste heat recovery provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the water and heat co-generation and co-transmission system combining power plant waste heat recovery in non-heating mode, provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the water and heat co-generation and co-transmission system combining power plant waste heat recovery in heating mode, provided in an embodiment of the present invention. Figure 5 This is a schematic diagram of the water and heat co-generation and co-transmission system combining power plant waste heat recovery in a high electricity price mode, provided in an embodiment of the present invention. Figure 6This is a schematic diagram of the water and heat co-generation and co-transmission system combining power plant waste heat recovery in a low electricity price mode, provided in an embodiment of the present invention.

[0020] Figure Labels 1. Seawater desalination unit; 2. Waste heat recovery unit; 21. Electric heat pump; 22. Absorption heat pump; 23. Peak heat exchanger; 24. Thermal storage electric boiler; 3. Combined power supply pipeline; 4. Water-heat separation unit; 41. User-end heating device; 5. Water supply unit; 6. Power generation unit; 61. Main steam turbine; 62. Small steam turbine; 63. Cooling unit; 101. First pipeline; 102. Second pipeline; 103. Third pipeline; 104. Fourth pipeline; 1041. Fourth branch pipeline; 1042. Fourth main pipeline; 105. Fifth pipeline; 106. Sixth inlet pipeline; 107. Sixth outlet pipeline; 201. First valve; 202. Second valve; 203. Third valve; 204. Fourth valve; 205. Fifth valve; 206. Sixth inlet valve; 207. Sixth outlet valve. Detailed Implementation

[0021] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, not all of them.

[0022] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0025] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 and Figure 2As shown, this embodiment provides a water and heat co-generation and transmission system combining power plant waste heat recovery, including a power generation unit 6, a seawater desalination unit 1, a waste heat recovery unit 2, a water and heat separation unit 4, and a water consumption unit 5. The power generation unit 6 includes a main steam turbine 61 and a small steam turbine 62. Main steam is fed into the main steam turbine 61 to generate electricity. High-grade exhaust steam generated by the main steam turbine 61 is fed into the small steam turbine 62 to generate electricity. Low-grade exhaust steam generated by the main steam turbine 61 is fed into the seawater desalination unit 1. The seawater desalination unit 1 is used to separate seawater into fresh water and saline. The fresh water is fed into the waste heat recovery unit 2 and / or the water consumption unit 5. In this embodiment, the seawater desalination unit 1 uses a membrane method for seawater desalination. Based on the principle of a semi-permeable membrane, under pressure higher than the osmotic pressure of seawater, water molecules in seawater can pass through the semi-permeable membrane, while solutes such as salt are retained, thereby achieving the separation of fresh water and salt and achieving the purpose of seawater desalination. The low-grade exhaust steam generated by the main steam turbine 61 is introduced into the seawater desalination unit 1 for preheating, which can improve the system performance of the seawater desalination unit 1, such as water flux, and can also reduce membrane fouling, reduce the required pressure, and thus reduce energy consumption. Waste heat recovery unit 2 includes an electric heat pump 21, an absorption heat pump 22, a peak heat exchanger 23, and a thermal storage electric boiler 24. Power generation unit 6 provides electricity to the electric heat pump 21 and the thermal storage electric boiler 24. Low-grade exhaust steam generated by the main steam turbine 61 heats the fresh water flowing within the electric heat pump 21 and the absorption heat pump 22, respectively. High-grade exhaust steam generated by the small steam turbine 62 and / or the thermal storage electric boiler 24 heat the fresh water flowing within the absorption heat pump 22 and the peak heat exchanger 23, respectively. Waste heat recovery unit 2 has a first water path including the cold side of the electric heat pump 21 and a second water path including the cold side of the absorption heat pump 22 and the cold side of the peak heat exchanger 23 connected in series. The electric heat pump 21, absorption heat pump 22, and peak heat exchanger 23 all have cold and hot sides. The hot side flows from the heat source of the power generation unit 6 (low-grade exhaust steam generated by the main turbine 61 and high-grade exhaust steam generated by the small turbine 62), while the cold side flows from the fresh water of the seawater desalination unit 1. The water-heat separation unit 4 is connected to the first water path and / or the second water path. The water-heat separation unit 4 is used to reduce the temperature of the fresh water, and the cooled fresh water flows to the water-using unit 5. That is, the fresh water separated by the seawater desalination unit 1 can be heated by the electric heat pump 21 and / or sequentially heated by the absorption heat pump 22 and the peak heat exchanger 23 to become hot water. The hot water is transported to the water-heat separation unit 4, where it is cooled by consuming heat. The cooled fresh water is then supplied to the water-using unit 5, thereby realizing the simultaneous production and transportation of water and heat during long-distance transportation. Secondly, in environments where heat is not required, the water supply unit 5 can be directly connected to the seawater desalination unit 1, meaning that the fresh water separated by the seawater desalination unit 1 can be directly supplied to the water supply unit 5 without heating.

[0027] In this embodiment, the low-grade exhaust steam generated by the main turbine 61 during power generation can directly enter the waste heat recovery unit 2 to heat the freshwater in the first water circuit via the electric heat pump 21. That is, the electric heat pump 21 directly utilizes the heat from the low-grade exhaust steam generated by the main turbine 61 to heat the freshwater before sending it out. Meanwhile, the high-grade exhaust steam generated by the main turbine 61 during power generation first enters the small turbine 62, where it further generates electricity while its grade is reduced before entering the waste heat recovery unit 2. That is, the low-grade exhaust steam generated by the small turbine 62 directly enters the waste heat recovery unit 2 to heat the freshwater in the second water circuit via the absorption heat pump 22 and the peak heat exchanger 23. The absorption heat pump 22 of the waste heat recovery unit 2 utilizes the heat from the high-grade exhaust steam from the small turbine 62 and the low-grade exhaust steam from the main turbine 61 to heat the freshwater, while the peak heat exchanger 23 directly utilizes the heat from the high-grade exhaust steam from the small turbine 62 and the heat from the thermal storage electric boiler 24 to heat the freshwater before sending it out. In this process, the small steam turbine 62 not only uses the high-grade exhaust steam of the main steam turbine 61 to generate electricity, but also adjusts the grade of its exhaust steam to match the waste heat recovery unit 2, reducing irreversible losses in the system.

[0028] The water and heat co-generation and co-transmission system provided in this embodiment combines water and heat transmission paths into one. It also adds a small steam turbine 62 and a waste heat recovery unit 2 to further utilize the waste heat from the main steam turbine 61. This system can transport water and heat from southern regions to northern regions, addressing the widespread water and heat shortages in the north, while reducing operating costs, improving system efficiency, and achieving clean and low-carbon development. Secondly, by setting up two modes—direct freshwater transmission and freshwater heated by the waste heat recovery unit 2 before transmission—the system can operate in both heating and non-heating modes, enabling year-round operation and expanding its application scenarios. Furthermore, the waste heat recovery unit 2 includes various heat exchange and storage devices such as an electric heat pump 21, an absorption heat pump 22, a peak heat exchanger 23, and a thermal storage electric boiler 24. This ensures the grid connection of the power generation unit 6 during periods of high electricity prices and absorbs excess electricity during periods of low electricity prices, thereby further reducing costs and also playing a role in peak shaving and valley filling, assisting in power system regulation.

[0029] Optionally, such as Figure 2As shown, the combined water and heat production and transportation system integrating power plant waste heat recovery also includes a combined supply and transportation pipeline 3. The first water path and the second water path are connected to the water-heat separation unit 4 through the combined supply and transportation pipeline 3. The freshwater outlet of the seawater desalination unit 1 is connected to the water-using unit 5 through the combined supply and transportation pipeline 3. The combined supply and transportation pipeline 3 is used for cross-regional transportation of freshwater or heated freshwater. The seawater desalination unit 1, waste heat recovery unit 2, and power generation unit 6 can be set up in area A, while the water-heat separation unit 4 and water-using unit 5 can be set up in area B. The first water path, the second water path, and the seawater desalination unit 1 in area A are all connected to the inlet end of the combined supply and transportation pipeline 3, thus realizing unified long-distance cross-regional transportation and reducing the number of pipelines in the combined supply and transportation pipeline 3. When the freshwater or heated freshwater flows to the outlet end of the combined supply and transportation pipeline 3, the freshwater is directly transported to the water-using unit 5, while the heated freshwater is transported to the water-heat separation unit 4, where it is cooled by consuming heat, and then the cooled freshwater is supplied to the water-using unit 5.

[0030] Optionally, such as Figure 2 As shown, the waste heat recovery unit 2 also includes a first valve 201 and a first pipeline 101. The first water path is connected to the combined power supply pipeline 3 via the first pipeline 101, and the first valve 201 is located on the first pipeline 101. The first water path only includes the cold side of the electric heat pump 21. Fresh water is heated by the cold side of the electric heat pump 21 and then continues to flow to the first pipeline 101. The first valve 201 controls the opening and closing of the first pipeline 101. When the first valve 201 is closed, the connection between the first water path and the water-heat separation unit 4 is interrupted; when the first valve 201 is open, the connection between the first water path and the water-heat separation unit 4 is restored. The first valve 201 is open in heating mode and low electricity price mode.

[0031] like Figure 2 As shown, the waste heat recovery unit 2 also includes a second valve 202 and a second pipeline 102. The second water path is connected to the combined heat and power supply pipeline 3 via the second pipeline 102, and the second valve 202 is located on the second pipeline 102. The second water path is formed by connecting the cold side of the absorption heat pump 22 and the cold side of the peak heat exchanger 23 in series. Fresh water is heated sequentially by passing through the cold side of the absorption heat pump 22 and the cold side of the peak heat exchanger 23 before continuing to flow to the second pipeline 102. The second valve 202 is used to control the opening and closing of the second pipeline 102. When the second valve 202 is closed, the connection between the second water path and the water-heat separation unit 4 is interrupted; when the second valve 202 is open, the connection between the second water path and the water-heat separation unit 4 is restored. The second valve 202 is open in heating mode, low electricity price mode, and high electricity price mode.

[0032] like Figure 2As shown, the seawater desalination unit 1 also includes a third valve 203 and a third pipeline 103. The freshwater outlet of the seawater desalination unit 1 is connected to the combined heat and power supply pipeline 3 via the third pipeline 103. The third valve 203 is located on the third pipeline 103. The third valve 203 is used to control the opening and closing of the third pipeline 103. When the third valve 203 is closed, the connection between the freshwater outlet and the combined heat and power supply pipeline 3 is interrupted; when the third valve 203 is open, the connection between the freshwater outlet and the combined heat and power supply pipeline 3 is restored. In non-heating mode, the third valve 203 is open.

[0033] Optionally, such as Figure 2 As shown, the water-heat separation unit 4 also includes a fourth valve 204 and a fourth pipeline 104. The water-heat separation unit 4 is connected to the combined power supply pipeline 3 via the fourth pipeline 104, and the fourth valve 204 is located on the fourth pipeline 104. The fourth valve 204 is used to control the opening and closing of the fourth pipeline 104. When the fourth valve 204 is closed, the connection between the water-heat separation unit 4 and the first pipeline 101, the second pipeline 102, and the third pipeline 103 is interrupted. When the fourth valve 204 is open, the fourth pipeline 104 is connected to the first pipeline 101 opened by the first valve 201, the second pipeline 102 opened by the second valve 202, and the third pipeline 103 opened by the third valve 203. The fourth valve 204 is open in heating mode, low electricity price mode, and high electricity price mode.

[0034] like Figure 2 As shown, the water-using unit 5 also includes a fifth valve 205 and a fifth pipeline 105. The water-using unit 5 is connected to the combined water supply pipeline 3 via the fifth pipeline 105, and the fifth valve 205 is located on the fifth pipeline 105. The fifth valve 205 is used to control the opening and closing of the fifth pipeline 105. When the fifth valve 205 is closed, the connection between the water-using unit 5 and the freshwater outlet of the seawater desalination unit 1 is interrupted, and when the third valve 203 is opened, the connection between the water-using unit 5 and the freshwater outlet of the seawater desalination unit 1 is restored. In non-heating mode, the fifth valve 205 is open.

[0035] Furthermore, the water-heat separation unit 4 includes multiple user-end heating devices 41 connected in parallel. The fourth pipeline 104 includes a connected fourth main pipe 1042 and multiple fourth branch pipes 1041, with each fourth branch pipe 1041 connecting to one user-end heating device 41. The fourth main pipe 1042 is connected to the combined supply and distribution pipeline 3. A fourth valve 204 is installed on the fourth main pipe 1042; opening the fourth valve 204 connects the multiple user-end heating devices 41 to the combined supply and distribution pipeline 3, while closing the fourth valve 204 disconnects them. Heated fresh water flowing out of the combined supply and distribution pipeline 3 enters the multiple user-end heating devices 41 connected in parallel. After heating, the temperature of the fresh water decreases before entering the water-using unit 5, which can be a waterworks. Additionally, depending on the user's needs, the user-end heating device 41 may take other forms, which will not be detailed here.

[0036] Optionally, the waste heat recovery unit 2 also includes a sixth valve and a sixth pipeline. The sixth valve is located on the sixth pipeline. The thermal storage electric boiler 24 is connected to the hot side of the peak heat exchanger 23 and the hot side of the absorption heat pump 22 through the sixth pipeline. The hot side of the peak heat exchanger 23 and the hot side of the absorption heat pump 22 are connected to the exhaust port of the small steam turbine 62. When the sixth valve is open, the heat generated by the thermal storage electric boiler 24 can heat the high-grade extraction steam flowing on the hot side of the peak heat exchanger 23 and the hot side of the absorption heat pump 22, and then use the heat exchange with the fresh water flowing in their respective cold sides to heat the fresh water flowing in the second water path. When the sixth valve is closed, the power generation unit 6 supplies electricity to the thermal storage electric boiler 24, enabling the thermal storage electric boiler 24 to switch to thermal storage mode. In thermal storage mode, electrical energy is converted into heat energy and stored, while in heat release mode, the stored heat energy is used to heat the fresh water in the above manner. The sixth valve is designed so that when the system is in a high electricity price mode, the thermal storage boiler 24 is in a heat release mode, and when the system is in a low electricity price mode, the thermal storage boiler 24 is in a heat storage mode.

[0037] Optionally, the sixth valve includes a sixth outlet valve 207 and a sixth inlet valve 206, and the sixth pipeline includes a sixth inlet pipeline 106 and a sixth outlet pipeline 107. The sixth outlet valve 207 is located on the sixth outlet pipeline 107, and the sixth inlet valve 206 is located on the sixth inlet pipeline 106. The outlet of the thermal storage electric boiler 24 is connected to the hot-side inlet of the peak heat exchanger 23 and the hot-side inlet of the absorption heat pump 22 via the sixth outlet pipeline 107. The inlet of the thermal storage electric boiler 24 is connected to the hot-side outlet of the peak heat exchanger 23 and the hot-side outlet of the absorption heat pump 22 via the sixth inlet pipeline 106. Two sixth outlet pipelines 107 are provided: one sixth outlet pipeline 107 connects the outlet of the thermal storage electric boiler 24, the exhaust port of the small steam turbine 62, and the hot-side inlet of the peak heat exchanger 23; the other sixth outlet pipeline 107 connects the outlet of the thermal storage electric boiler 24, the exhaust port of the small steam turbine 62, and the hot-side inlet of the absorption heat pump 22. Two sixth inlet pipes 106 are provided. One sixth inlet pipe 106 connects the inlet of the thermal storage electric boiler 24 and the hot-side outlet of the peak heat exchanger 23, and the other sixth inlet pipe 106 connects the inlet of the thermal storage electric boiler 24 and the hot-side outlet of the absorption heat pump 22.

[0038] Optionally, the power generation unit 6 also includes a cooling unit 63, which is connected to the exhaust steam inlet of the main steam turbine 61 and the exhaust steam inlet of the small steam turbine 62. That is, the low-grade exhaust steam from the main steam turbine 61 and the small steam turbine 62 can be directly recovered by the cooling unit 63. The cooling unit 63 is also connected to the hot-side outlet of the seawater desalination unit 1, the hot-side outlet of the electric heat pump 21, the hot-side outlet of the absorption heat pump 22, and the hot-side outlet of the peak heat exchanger 23. The low-grade exhaust steam from the main turbine 61 can also be recycled to the cooling unit 63 after exchanging heat with the cold side of the seawater desalination unit 1 on the hot side. The low-grade exhaust steam from the main turbine 61 can also be recycled to the cooling unit 63 after exchanging heat with the cold side of the electric heat pump 21 on the hot side. The high-grade exhaust steam from the main turbine 61 can be recycled to the cooling unit 63 after generating electricity in the small turbine 62 to further reduce its grade, and then flow from the exhaust port of the small turbine 62 to the hot side of the absorption heat pump 22 and the hot side of the peak heat exchanger 23, exchange heat with their respective cold sides, and then be recycled to the cooling unit 63.

[0039] This embodiment also provides an operating method applied to the aforementioned combined power plant waste heat recovery hydrothermal co-generation and transmission system. The operating method includes the following steps: like Figure 3As shown, in the non-heating mode of the combined water and heat production and transmission system integrating power plant waste heat recovery, the main steam turbine 61 and the seawater desalination unit 1 are operating. The low-grade exhaust steam generated by the main steam turbine 61 preheats the seawater desalination unit 1, and the freshwater from the seawater desalination unit 1 is supplied to the water-using unit 5. That is, in the non-heating mode, only the main steam turbine 61 generates electricity, and the low-grade exhaust steam generated during the power generation process preheats the seawater desalination unit 1 to improve the system performance such as the water flux of the seawater desalination unit 1, reduce membrane fouling, reduce the required pressure, and thus reduce energy consumption. The resulting freshwater is directly transported to the water-using unit 5 through the combined supply and distribution pipeline 3. Since no heating is required, there is no need for combined water and heat transmission.

[0040] In specific implementation, such as Figure 3 As shown, the water and heat production and transmission system combined with power plant waste heat recovery is in non-heating mode. The first valve 201, the second valve 202 and the sixth valve of the waste heat recovery unit 2 are closed, the fourth valve 204 of the water and heat separation unit 4 is closed, the third valve 203 of the seawater desalination unit 1 is open and the fifth valve 205 of the water use unit 5 is open.

[0041] like Figure 4 As shown, the combined water and heat production and transmission system, which integrates waste heat recovery from the power plant, is in heating mode. The seawater desalination unit 1, main steam turbine 61, small steam turbine 62, electric heat pump 21, absorption heat pump 22, peak heat exchanger 23, and thermal storage electric boiler 24 are all operating. The low-grade exhaust steam generated by the main steam turbine 61 preheats the seawater desalination unit 1. The freshwater from the desalination unit 1 is heated through the first and second water passages and then flows into the water-heat separation unit 4. The water-heat separation unit 4 lowers the temperature of the freshwater, which then flows to the water consumption unit 5. The high-grade exhaust steam generated by the main steam turbine 61 enters the small steam turbine 62 for power generation. The high-grade exhaust steam generated by the small steam turbine 62 enters the hot side of the peak heat exchanger 23 and the hot side of the absorption heat pump 22, working together with the thermal storage electric boiler 24 to heat the freshwater flowing in the second water passage. The low-grade exhaust steam generated by the main steam turbine 61 enters the hot side of the electric heat pump 21 to heat the freshwater flowing in the first water passage. In heating mode, the small steam turbine 62 uses the high-grade exhaust steam from the main steam turbine 61 to generate electricity. At the same time, adjusting the exhaust grade of the small steam turbine 62 to match the waste heat recovery unit 2 can reduce irreversible losses in the system.

[0042] In specific implementation, such as Figure 4 As shown, the water and heat production and transmission system combined with power plant waste heat recovery is in heating mode. The first valve 201, the second valve 202 and the sixth valve of the waste heat recovery unit 2 are open, the fourth valve 204 of the water and heat separation unit 4 is open, the third valve 203 of the seawater desalination unit 1 is closed and the fifth valve 205 of the water use unit 5 is closed.

[0043] like Figure 5As shown, the combined water and heat production and transmission system, which integrates waste heat recovery from the power plant, operates under a high electricity price mode. The seawater desalination unit 1, main steam turbine 61, absorption heat pump 22, and peak heat exchanger 23 are all in operation, while the thermal storage boiler 24 operates in heat release mode. The low-grade exhaust steam generated by the main steam turbine 61 preheats the seawater desalination unit 1. The freshwater from the desalination unit 1 is heated through the second water path and then flows into the water-heat separation unit 4. The water-heat separation unit 4 lowers the temperature of the freshwater, which then flows to the water consumption unit 5. The thermal storage boiler 24 operates in heat release mode, and it is connected to the hot side of the peak heat exchanger 23 and the hot side of the absorption heat pump 22 to heat the freshwater flowing in the second water path. In the high electricity price mode, the small steam turbine 62 and the electric heat pump 21 both stop operating, and the thermal storage electric boiler 24 switches to the heat release mode. This is the peak electricity consumption period. The heat stored in the thermal storage electric boiler 24 and the heat utilization of the low-grade exhaust steam of the main steam turbine 61 improve the system's economy and ensure grid-connected power.

[0044] In specific implementation, such as Figure 5 As shown, the water and heat co-generation and co-transmission system combining power plant waste heat recovery is in a high electricity price mode. The second valve 202 and the sixth valve of waste heat recovery unit 2 are open, the fourth valve 204 of water and heat separation unit 4 is open, the first valve 201 of waste heat recovery unit 2 is closed, the third valve 203 of seawater desalination unit 1 is closed, and the fifth valve 205 of water use unit 5 is closed.

[0045] like Figure 6 As shown, the combined water and heat production and transmission system, which integrates waste heat recovery from the power plant, operates in a low-electricity-price mode. The seawater desalination unit 1, main steam turbine 61, small steam turbine 62, absorption heat pump 22, and peak heat exchanger 23 are all in operation, while the thermal storage electric boiler 24 operates in thermal storage mode. The low-grade exhaust steam generated by the main steam turbine 61 preheats the seawater desalination unit 1. The freshwater from the desalination unit 1 is heated through the first and second water paths and then flows into the water-heat separation unit 4. The water-heat separation unit 4 lowers the temperature of the freshwater, which then flows to the water-using unit 5. The high-grade exhaust steam generated by the main steam turbine 61 enters the small steam turbine 62 to generate electricity. The high-grade exhaust steam generated by the small steam turbine 62 enters the hot side of the peak heat exchanger 23 and the hot side of the absorption heat pump 22 to heat the freshwater flowing in the second water path. The low-grade exhaust steam generated by the main steam turbine 61 enters the hot side of the electric heat pump 21 to heat the freshwater flowing in the first water path. In the low-electricity-price mode, freshwater is divided into two streams. One stream is heated by the electric heat pump 21 and then sent out directly. The other stream is heated sequentially by the absorption heat pump 22 and the peak heat exchanger 23 before being sent out. The small steam turbine 62 and the electric heat pump 21 operate normally. At the same time, the excess off-peak electricity is used to recover the waste heat of the exhaust steam to heat the freshwater and store the heat in the thermal storage electric boiler 24. This can reduce the energy demand of the power generation unit 6 during peak electricity consumption periods, thereby achieving thermoelectric decoupling and assisting in the regulation of the power system.

[0046] In specific implementation, such as Figure 6 As shown, in the low electricity price mode, the water and heat production and transmission system combined with the power plant waste heat recovery is in a low electricity price mode. The first valve 201 and the second valve 202 of the waste heat recovery unit 2 are open, the fourth valve 204 of the water and heat separation unit 4 is open, the sixth valve of the waste heat recovery unit 2 is closed, the third valve 203 of the seawater desalination unit 1 is closed, and the fifth valve 205 of the water use unit 5 is closed.

[0047] The above embodiments merely illustrate the basic principles and characteristics of the present invention. The present invention is not limited to the above embodiments. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hydrothermal cogeneration and co-transmission system combined with waste heat recovery of a power plant, characterized in that, It includes a power generation unit (6), a seawater desalination unit (1), a waste heat recovery unit (2), a water and heat separation unit (4), and a water use unit (5); The power generation unit (6) includes a main steam turbine (61) and a small steam turbine (62). The main steam is fed into the main steam turbine (61) to generate electricity. The high-grade exhaust steam generated by the main steam turbine (61) is fed into the small steam turbine (62) to generate electricity. The low-grade exhaust steam generated by the main steam turbine (61) is fed into the seawater desalination unit (1). The seawater desalination unit (1) is used to separate seawater into fresh water and salt. The fresh water is fed into the waste heat recovery unit (2) and / or the water use unit (5). The waste heat recovery unit (2) includes an electric heat pump (21), an absorption heat pump (22), a peak heat exchanger (23), and a thermal storage electric boiler (24). The power generation unit (6) is used to provide power to the electric heat pump (21) and the thermal storage electric boiler (24). The low-grade exhaust steam generated by the main steam turbine (61) heats the fresh water flowing in the electric heat pump (21) and the absorption heat pump (22), respectively. The high-grade exhaust steam generated by the small steam turbine (62) and / or the thermal storage electric boiler (24) heat the fresh water flowing in the absorption heat pump (22) and the peak heat exchanger (23), respectively. The waste heat recovery unit (2) has a first water path including the cold side of the electric heat pump (21) and a second water path including the cold side of the absorption heat pump (22) connected in series and the cold side of the peak heat exchanger (23). Fresh water is connected to the water heat separation unit (4) through the first water path and / or the second water path. The water heat separation unit (4) is used to reduce the temperature of the fresh water. The cooled fresh water is then directed to the water use unit (5).

2. The hydrothermal co-production and co-transport system combined with waste heat recovery of power plants according to claim 1, characterized in that, The combined water and heat production and transmission system that integrates power plant waste heat recovery also includes a combined supply and transmission pipeline (3). The first water path and the second water path are connected to the water and heat separation unit (4) through the combined supply and transmission pipeline (3). The freshwater outlet of the seawater desalination unit (1) is connected to the water-using unit (5) through the combined supply and transmission pipeline (3).

3. The hydrothermal co-production and co-transport system combined with waste heat recovery of power plants according to claim 2, characterized in that, The waste heat recovery unit (2) further includes a first valve (201) and a first pipeline (101). The first water path is connected to the combined power supply pipeline (3) through the first pipeline (101). The first valve (201) is located on the first pipeline (101). The waste heat recovery unit (2) also includes a second valve (202) and a second pipeline (102). The second water path is connected to the combined power supply pipeline (3) through the second pipeline (102). The second valve (202) is installed on the second pipeline (102). The seawater desalination unit (1) also includes a third valve (203) and a third pipeline (103). The freshwater outlet of the seawater desalination unit (1) is connected to the combined supply pipeline (3) through the third pipeline (103). The third valve (203) is located on the third pipeline (103).

4. The hydrothermal co-production and co-transport system combined with waste heat recovery of power plants according to claim 2, characterized in that, The water-heat separation unit (4) further includes a fourth valve (204) and a fourth pipeline (104). The water-heat separation unit (4) is connected to the combined power supply pipeline (3) through the fourth pipeline (104). The fourth valve (204) is located on the fourth pipeline (104). The water-using unit (5) also includes a fifth valve (205) and a fifth pipeline (105). The water-using unit (5) is connected to the combined power supply pipeline (3) through the fifth pipeline (105). The fifth valve (205) is located on the fifth pipeline (105).

5. The water-heat co-generation and co-transmission system combining power plant waste heat recovery according to claim 4, characterized in that, The water-heat separation unit (4) includes multiple user-end heating devices (41) arranged in parallel. The fourth pipeline (104) includes a fourth main pipe (1042) and multiple fourth branch pipes (1041) connected together. One of the fourth branch pipes (1041) is connected to one of the user-end heating devices (41). The fourth main pipe (1042) is connected to the combined supply and delivery pipeline (3). The fourth valve (204) is located on the fourth main pipe (1042).

6. The water and heat co-generation and co-transmission system combining power plant waste heat recovery according to claim 1, characterized in that, The waste heat recovery unit (2) also includes a sixth valve and a sixth pipeline. The sixth valve is located on the sixth pipeline. The thermal storage electric boiler (24) is connected to the hot side of the peak heat exchanger (23) and the hot side of the absorption heat pump (22) through the sixth pipeline. The hot side of the peak heat exchanger (23) and the hot side of the absorption heat pump (22) are connected to the exhaust port of the small steam turbine (62).

7. The water and heat co-generation and co-transmission system combining power plant waste heat recovery according to claim 6, characterized in that, The sixth valve includes a sixth outlet valve (207) and a sixth inlet valve (206), and the sixth pipeline includes a sixth outlet pipeline (107) and a sixth inlet pipeline (106). The sixth outlet valve (207) is disposed on the sixth outlet pipeline (107), and the sixth inlet valve (206) is disposed on the sixth inlet pipeline (106). The outlet of the thermal storage electric boiler (24) is connected to the hot side inlet of the peak heat exchanger (23) and the hot side inlet of the absorption heat pump (22) through the sixth outlet pipe (107), and the inlet of the thermal storage electric boiler (24) is connected to the hot side outlet of the peak heat exchanger (23) and the hot side outlet of the absorption heat pump (22) through the sixth inlet pipe (106).

8. The water and heat co-generation and co-transmission system combining power plant waste heat recovery according to claim 1, characterized in that, The power generation unit (6) also includes a cooling unit (63), which is connected to the exhaust port of the main steam turbine (61) and the exhaust port of the small steam turbine (62). The cooling unit (63) is also connected to the hot-side outlet of the seawater desalination unit (1), the hot-side outlet of the electric heat pump (21), the hot-side outlet of the absorption heat pump (22), and the hot-side outlet of the peak heat exchanger (23).

9. The operating method, characterized in that, The operating method of the combined hydro-thermal system with waste heat recovery from a power plant, as described in any one of claims 1 to 8, comprises the following steps: The combined water and heat production and transmission system that integrates power plant waste heat recovery is in non-heating mode. The main steam turbine (61) and the seawater desalination unit (1) are in operation. The low-grade exhaust steam generated by the main steam turbine (61) preheats the seawater desalination unit (1), and the fresh water from the seawater desalination unit (1) is supplied to the water-using unit (5). The combined water and heat production and transmission system integrating power plant waste heat recovery is in heating mode. The seawater desalination unit (1), the main steam turbine (61), the small steam turbine (62), the electric heat pump (21), the absorption heat pump (22), and the peak heat exchanger (23) are all in operation. The high-grade exhaust steam generated by the main steam turbine (61) is fed into the small steam turbine (62) for power generation. The low-grade exhaust steam generated by the main steam turbine (61) preheats the seawater desalination unit (1). The fresh water from the seawater desalination unit (1) is heated through the first water path and the second water path and then flows into the water and heat separation unit (4). The water and heat separation unit (4) is used to reduce the temperature of the fresh water. The cooled fresh water is then fed into the water-using unit (5). The combined hydro-thermal system, which integrates waste heat recovery from the power plant, operates under a high electricity price mode. The seawater desalination unit (1), the main steam turbine (61), the absorption heat pump (22), and the peak heat exchanger (23) are all in operation. The thermal storage electric boiler (24) operates in a heat release mode. The low-grade exhaust steam generated by the main steam turbine (61) preheats the seawater desalination unit (1). The freshwater from the seawater desalination unit (1) is heated through the second water path and then flows into the hydro-thermal separation unit (4). The hydro-thermal separation unit (4) is used to reduce the temperature of the freshwater. The cooled freshwater then flows to the water-using unit (5). The combined hydro-thermal system, which integrates waste heat recovery from the power plant, operates under a low electricity price mode. The seawater desalination unit (1), the main steam turbine (61), the small steam turbine (62), the absorption heat pump (22), and the peak heat exchanger (23) are all in operation. The thermal storage electric boiler (24) operates in thermal storage mode. The high-grade exhaust steam generated by the main steam turbine (61) is fed into the small steam turbine (62) for power generation. The low-grade exhaust steam generated by the main steam turbine (61) preheats the seawater desalination unit (1). The freshwater from the seawater desalination unit (1) is heated through the first water path and the second water path and then flows into the hydro-thermal separation unit (4). The hydro-thermal separation unit (4) is used to reduce the temperature of the freshwater. The cooled freshwater flows to the water-using unit (5).

10. The operating method according to claim 9, characterized in that, The operating method includes the following steps: The combined water and heat production and transmission system that integrates power plant waste heat recovery is in non-heating mode. The first valve (201), the second valve (202) and the sixth valve of the waste heat recovery unit (2) are closed, the fourth valve (204) of the water and heat separation unit (4) is closed, the third valve (203) of the seawater desalination unit (1) is open, and the fifth valve (205) of the water use unit (5) is open. The combined water and heat production and transmission system that integrates power plant waste heat recovery is in heating mode. The first valve (201), the second valve (202) and the sixth valve of the waste heat recovery unit (2) are open, the fourth valve (204) of the water and heat separation unit (4) is open, the third valve (203) of the seawater desalination unit (1) is closed, and the fifth valve (205) of the water use unit (5) is closed. The combined water and heat production and transmission system that integrates power plant waste heat recovery is in a high electricity price mode. The second valve (202) and the sixth valve of the waste heat recovery unit (2) are open, the fourth valve (204) of the water and heat separation unit (4) is open, the first valve (201) of the waste heat recovery unit (2) is closed, the third valve (203) of the seawater desalination unit (1) is closed, and the fifth valve (205) of the water use unit (5) is closed. The combined water and heat production and transmission system that integrates power plant waste heat recovery is in a low electricity price mode. The first valve (201) and the second valve (202) of the waste heat recovery unit (2) are open, the fourth valve (204) of the water and heat separation unit (4) is open, the sixth valve of the waste heat recovery unit (2) is closed, the third valve (203) of the seawater desalination unit (1) is closed, and the fifth valve (205) of the water use unit (5) is closed.

Images